Download Potential Changes in Future Surface Water Temperatures

Note Number 7
2008
Potential Changes in Future Surface Water Temperatures in
the Ontario Great Lakes as a Result of Climate Change
J. Trumpickas1,2, B.J. Shuter1,2 and C.K. Minns1,3
Climate change is expected to have numerous effects on freshwater systems, including changes to water clarity, water levels, pH,
ice cover, and surface water temperatures (Magnuson et al. 1997). The increased water temperatures that are expected to result from
climate change will have important biological effects, such as changing the distribution of fish species (Chu et al. 2005), facilitating the
spread of warm-water species into new habitats (Sharma et al. 2007), increasing the length of the growing season, and changing the
availability and distribution of different habitat types within a lake (Ficke et al. 2007).
The Great Lakes Basin contains 20% of the world’s freshwater and supports a human population of more than 30 million (Magnuson
et al. 1997). Thus, it is important to understand the potential effects of climate change on this system, and a number of recent studies
have begun to do so. Several have found trends that indicate recent increases in water temperature. For example, McCormick and
Fahnenstiel (1999) found evidence of increasing water temperature at five out of seven near-shore sites in the Great Lakes over the
past 25 to 87 years, and increases in the length of the period of summer temperature stratification at several sites. Jones et al. (2006)
found increasing summer water temperatures and decreasing winter length in western Lake Erie, as has been predicted by most
climate change models. Dobiesz and Lester (in prep.) detected significant increases in summer water temperatures for Lake Huron,
Lake Ontario, and the central basin of Lake Erie, whereas Assel (2005) found a decrease in the occurrence of severe winter ice cover
between 1998 and 2002 compared with coverage between 1977 and 1982. Similarly, Austin and Colman (2007) observed increasing
summer water temperatures in Lake Superior between 1979 and 2006, coupled with a decrease in winter ice cover.
The goal of the present study was to predict surface water temperatures in Lake Superior, Lake Huron, Lake Erie, and Lake Ontario
during three time periods (2011 to 2040, 2041 to 2070, and 2071 to 2100, with 1971 to 2000 used as the base period) under two
different warming scenarios (IPCC A2 and B2 CO2-equivalent scenarios; Nakicenovik et al. 2000). To do so, we used historical data
to develop empirical models of the links between climate and water temperature conditions, and then used those models to translate
forecasts of future climate into forecasts of future water temperatures.
Methods
Characterizing Annual Water Temperature Cycles
We used remotely sensed whole-lake surface water temperatures
(SWT) from the NOAA Great Lakes Surface Environment Analysis
(GLSEA) program (http://coastwatch.glerl.noaa.gov/overview/cwoverview.html) to model water temperatures in Lake Superior, Lake
Huron, Lake Erie, and Lake Ontario from 1995 to 2006. We fitted a simple
model (Figure 1) consisting of three parts: a spring warming period, a
period of maximum mid-summer temperature, and a fall cooling period.
To determine the spring warming and fall cooling rates, we classified
data from individual lakes into spring, summer, and fall periods as
follows. Care was taken to focus on those periods in each year that
exhibited strong and consistent increasing (spring) or decreasing (fall)
trends in temperature. Figure 2 shows data for Lake Superior, which are
representative of the patterns for the other lakes. Thus, any temperatures
less than 7°C were not used from Lake Huron and Lake Ontario, and
temperatures less than 6°C were not used from Lake Superior and Lake
Erie.
Figure 1. Conceptual diagram of the surface water temperature model.
Spring slopes (A) and fall slopes (C) are consistent for a lake, but the
x-intercepts vary annually. The value of the summer plateau (B) varies
annually. J10 values are the days of the year in the spring and fall when
the temperature is 10°C. Tmax determines the temperature of the summer
plateau and is estimated as the median of the ten highest temperatures
observed during the year.
Department of Ecology and Evolutionary Biology, University of Toronto, ON M5S 3G5, Canada
Harkness Laboratory of Fisheries Research, Aquatic Ecosystem Science Section, Ontario Ministry of Natural Resources, 300 Water St., Peterborough, ON K9J 8M5 Canada
3
Great Lakes Laboratory for Fisheries and Aquatic Science, Fisheries and Oceans Canada, PO Box 5050, 867 Lakeshore Road, Burlington ON L7R 4A6, Canada
1
2
Applied Research and Development Branch
http://www.mnr.gov.on.ca/en/Business/ClimateChange/index.html
C L I M AT E
CHANGE
RESEARCH
I N F O R M AT I O N
NOTE
Figure 2. Linear models of surface water temperatures vs. day of year in the spring (left) and fall (right) for Lake Superior from 1995 to 2006.
Since the observed year-to-year variation in the rates of spring and fall temperature changes was quite low for each lake (Figure 3),
the spring warming and fall cooling periods could be represented reasonably well by assuming a linear spring warming and fall cooling
trend, with a slope that was fixed across years and x-intercept values that varied from year to year. We used analysis of covariance
(ANCOVA) to fit this model to the spring and fall data for each lake. This allowed us to estimate the day of the year (DOY) in spring when
temperatures had increased to 10°C (J10spring) and the day of the year in fall when temperatures had fallen to 10°C (J10fall). Temperatures
during the interval between the spring warming period and the fall cooling period could be represented reasonably well by a lake-specific
constant that varied from year to year. The value of this constant (Tmax) for a particular year was estimated as the median of the ten
highest daily water temperatures observed in that year.
Figure 3. Boxplots showing the variation in the rates of spring and fall surface water temperature changes (slopes) from 1995 to 2006 for the Great Lakes in
Ontario.
Thus, we were able to represent the annual surface water temperature cycles for each lake from 1995 to 2006 using a simple
three-part model that consisted of a lake-specific spring slope with year-specific x-intercepts, a lake- and year-specific summer plateau
temperature, and a lake-specific fall slope with year-specific x-intercepts. This scheme allowed us to specify the annual temperature
cycle for a particular lake in a particular year using only two lake-specific parameters (the spring and fall slopes) and three year-specific
parameters (J10spring, Tmax, and J10fall).
Using the GLSEA data, we calculated the length of the winter and ice-free periods in each year. We defined the length of the winter
as the predicted number of days with temperatures less than 4°C and the length of the ice-free period as the predicted number of days
with temperatures above 4°C. Winter length was calculated as a continuous season between days with these two temperatures from the
fall of one year to the spring of the following year.
Linking Historical Variation in Water Temperature Cycles to Historical Variation in Climate
Climate data was obtained from three Environment Canada climate stations for each of the four Great Lakes. Monthly, seasonal,
and annual means were calculated and correlations between stations and climate means were calculated. Overall, correlations among
stations were high for a given lake, with Pearson correlations ranging from 0.86 to 0.98. This result, combined with the reported
significant correlation of mean air temperatures over distances of up to 2,500 km (Koenig 2002), suggests that it would be feasible to use
data from a single climate station per lake in our subsequent analyses. The stations we used were those in Sault Ste. Marie, Sudbury,
Windsor, and Trenton for Lake Superior, Lake Huron, Lake Erie, and Lake Ontario, respectively.
2
C L I M AT E
CHANGE
RESEARCH
I N F O R M AT I O N
NOTE
Using monthly and 6- and 12-month mean air temperatures as independent variables and Tmax, J10spring, and J10fall as dependent
variables, we performed a best-subsets regression for each lake. For each water temperature parameter, we chose a set of three or
four climate variables as the set of best predictors. These regression models were then used to predict future water temperatures from
forecasts of future climates. In this analysis, we used the IPCC A2 and B2 CO2-equivalent scenarios as sources for predicted future
mean monthly air temperatures for the periods 2011 to 2040, 2041 to 2070, and 2071 to 2100 for each climate station. The A2 scenario
is characterized by high population growth and energy use, whereas the B2 scenario reflects moderate population growth and energy
use (Nakicenovic et al. 2000). Any discrepancies between the Environment Canada and calculated air temperature values for the 1971
to 2000 base period were accounted for in generating our predictions of the future climate. Predicted J10spring and J10fall values were
used to estimate the annual number of days in each year with a temperature <4°C.
Results and Discussion
During the base period, Tmax appeared to increase slightly
in all lakes, but the changes were not significant (ANCOVA, p =
0.3816; Figure 4). However, changes in the lengths of the winter
and ice-free periods were significant (Figure 5). For all four lakes,
winter length decreased significantly (ANCOVA, p = 0.0036)
and the length of the ice-free period increased significantly
(ANCOVA, p = 0.0268). Although it is possible that these trends
reflect large-scale patterns associated with climate change, the
timespan of the data set is too short for this hypothesis to be
conclusive. As noted by McCormick and Fahnenstiel (1999),
the specific interval of data being examined in climate change
studies can significantly affect results.
Regression values from the surface water temperature model
revealed interesting patterns. Lake-specific warming and cooling
rates were not significantly different for Lake Ontario, Lake Erie,
and Lake Huron, but warming was faster and cooling slower for
Lake Superior (Table 1). Fitting common slopes to the multiyear data for each lake worked well, with adjusted R2 values
ranging from 0.8050 to 0.9530. Year-specific x-intercept values
for spring and fall varied widely, both within and between lakes.
The resulting J10 values showed greater variation in the spring
than in the fall (Figure 6). Tmax also varied widely both within and
between lakes (Figure 7).
The regressions of Tmax, J10spring, and J10fall against SWT
yielded high adjusted R2 values, ranging from 0.74 to 0.91 for
Tmax, 0.79 to 0.90 for J10spring, and 0.53 to 0.84 for J10fall (Tables
2-4). All models were significant at p < 0.05 except for the
Lake Huron J10fall model, which was marginally significant (p =
0.0507). Future SWT values predicted using these models are
presented in Tables 5 through 12 and illustrated in Figure 8. By
Figure 4. Changes in Tmax values from 1995 to 2006 for Lake Superior, Lake
Huron, Lake Erie, and Lake Ontario. Tmax values did not increase significantly
over this time span (ANCOVA, p = 0.3816). Tmax represents the median of the
ten highest temperatures observed in a lake during the year.
Lake
Season
Slopea
Adjusted R2
Superior
Spring
Fall
Spring
Fall
Spring
Fall
Spring
Fall
0.22448
-0.13947
0.19197
-0.16170
0.19409
-0.16211
0.19268
-0.17516
0.8442
0.9098
0.8281
0.9478
0.9022
0.9530
0.8050
Huron
Erie
Ontario
a
Table 1. Fitted
slopes for the
rates of change
in fall and spring
surface water
temperatures.
All fitted models were significant at p < 0.0001.
Figure 5. Lengths of the winter (temperature <4°C) and spring, summer, and fall (temperature >4°C) periods from 1995 to 2006 for Lake Superior, Lake Huron,
Lake Erie, and Lake Ontario. Winter length decreased significantly (ANCOVA, p = 0.0036), and the length of the ice-free period increased significantly (ANCOVA, p
= 0.0268).
3
C L I M AT E
CHANGE
RESEARCH
I N F O R M AT I O N
NOTE
Figure 6. Boxplots showing the variation in spring and fall J10 values for Lake Superior, Lake Huron, Lake Erie, and Lake Ontario from 1995 to 2006. J10 is the
day of the year in which the surface water temperature reached 10°C.
Figure 7. Boxplots demonstrating between-lake and between-year variation in
Tmax values for the four lakes. Tmax was estimated as the median of the ten highest
temperatures observed in a lake during the year.
P value
Adjusted R2
0.51
0.0028
0.7422
0.49
0.06
0.0024
0.7515
0.56
0.43
-0.18
<0.0001
0.9149
0.44
0.60
-0.01
0.0026
0.7483
Lake
Constant
Julymean
Superior
8.52
0.20
0.26
Huron
1.74
0.54
Erie
3.42
Ontario
1.96
Lake
Constant
Aprilmean
Maymean
Superior
198.52
-3.91
-0.89
0.14
Huron
196.19
-2.14
-0.29
-2.65
Erie
218.63
-1.48
-1.48
Ontario
244.78
-2.34
-0.61
Lake
Constant
Septmean
Superior
178.35
Huron
Augustmean January to Junemean
Junemean Oct-Marmean
P value Adjusted R2
0.0018
0.8283
-4.31
0.0003
0.8956
-2.33
-3.67
0.0011
0.8502
-4.19
-1.06
0.0033
0.7941
Octmean Mar-Augmean Sept-Augmean
P value
Adjusted R2
2.00
3.44
2.73
2.96
0.0028
0.8042
273.15
2.03
2.49
-3.22
5.24
0.0507
0.5294
Erie
245.12
2.26
2.94
0.37
-0.18
0.0013
0.8440
Ontario
242.54
2.89
4.44
-4.78
5.69
0.0039
0.7833
4
Table 2. Regression of median of the
ten highest temperatures observed in
a lake during the year (Tmax) versus
surface water temperature.
Table 3. Regression of day of the year
in which the surface water temperature
reached 10°C (J10spring) versus surface
water temperature.
Table 4. Regression of day of the year
in which the surface water temperature
reached 10°C (J10fall) versus surface
water temperature.
C L I M AT E
CHANGE
RESEARCH
I N F O R M AT I O N
NOTE
the 2071 to 2100 period, maximum surface temperatures (Tmax) are expected to rise by 3.7 to 4.4°C under the A2 scenario and by 2.5
to 3.1°C under the B2 scenario. Spring J10 values occur 34.8 to 46.5 days earlier under A2 and 23.8 to 30.7 days earlier under B2. In
contrast, the fall J10 values will occur 26.2 to 51.2 days later under A2 and 17.7 to 36.1 days later under B2. These changes translate
into a decrease in winter length of from 42 days for Lake Erie under B2 to 90 days for Lake Superior under A2 between the 1971 to
2000 period and the 2071 to 2100 period. (Tables 13 through 16 and Figures 9 and 10 provide the full prediction results.) The overall
estimated changes for each lake between the 30-year base period and the 2071-2100 period for the A2 scenario are illustrated in
Figure 11. The same overall pattern was observed for the B2 scenario (data not shown).
Table 5. Predicted surface water temperatures for Lake Superior.1
PeriodS
1971-2000
2011-2040
2041-2070
2071-2100
Scenario S Tmax( C) J10spring(DOY)
a
Base
A2
B2
A2
B2
A2
B2
0
16.7
18.0
18.1
19.3
18.9
21.2
19.8
195.8
185.8
183.4
174.0
178.2
157.5
169.8
Table 9. Predicted changes in surface water temperatures from the
1971-2000 average for Lake Superior.1
J10fall(DOY)
a
IPCC CO2-equivalent scenarios
a
Table 6. Predicted surface water temperatures for Lake Huron.1
PeriodS
1971-2000
2011-2040
2041-2070
2071-2100
ScenarioaS Tmax(0C) J10spring(DOY)
Base
A2
B2
A2
B2
A2
B2
20.6
22.1
21.9
23.1
22.7
25.0
23.5
IPCC CO2-equivalent scenarios
a
164.6
156.5
154.8
144.8
148.2
129.4
140.5
1971-2000
2011-2040
2041-2070
2071-2100
a
ScenarioaS Tmax(0C) J10spring(DOY)
Base
A2
B2
A2
B2
A2
B2
24.2
25.3
25.0
25.8
25.9
27.9
26.7
IPCC CO2-equivalent scenarios
136.2
125.2
124.5
115.3
118.8
101.4
112.4
J10fall(DOY)
ScenarioaS Tmax(0C)
+1.4
A2
2011-2040
+1.3
B2
+2.4
A2
2041-2070
+2.1
B2
+4.3
A2
2071-2100
+2.9
B2
PeriodS
298.8
306.9
307.8
315.6
312.4
325.7
319.5
a
PeriodS
1971-2000
2011-2040
2041-2070
2071-2100
a
Scenario S Tmax(0C) J10spring(DOY)
Base
A2
B2
A2
B2
A2
B2
22.6
23.9
23.8
24.9
24.7
27.0
25.5
152.7
142.7
140.4
127.1
131.4
106.2
122.0
+1.3
+1.4
+2.6
+2.1
+4.4
+3.1
J10fal
+15.0
+16.6
+29.6
+24.5
+51.2
+36.1
J10spring
-8.1
-9.8
-19.8
-16.5
-35.2
-24.1
J10fal
+8.1
+9.1
+16.8
+13.7
+26.9
+20.7
IPCC CO2-equivalent scenarios
Table 11. Predicted changes in surface water temperatures from the
1971-2000 average for Lake Erie.1
J10fall(DOY)
ScenarioaS Tmax(0C)
+1.1
A2
2011-2040
+0.8
B2
+1.6
A2
2041-2070
+1.7
B2
+3.7
A2
2071-2100
+2.5
B2
PeriodS
320.6
327.1
327.2
335.5
333.0
346.9
338.3
a
Table 8. Predicted surface water temperatures for Lake Ontario.1
a
IPCC CO2-equivalent scenarios
J10spring
Table 10. Predicted changes in surface water temperatures from the
1971-2000 average for Lake Huron.1
Table 7. Predicted surface water temperatures for Lake Erie.1
PeriodS
ScenarioaS Tmax(0C)
-10.0
A2
2011-2040
-12.4
B2
-21.8
A2
2041-2070
B2
-17.6
A2
-38.3
2071-2100
-26.0
B2
PeriodS
280.4
295.5
297.1
310.1
305.0
331.7
316.6
J10spring
-11.0
-11.6
-20.8
-17.4
-34.8
-23.8
J10fal
+6.5
+6.6
+14.8
+12.4
+26.2
+17.7
IPCC CO2-equivalent scenarios
Table 12. Predicted changes in surface water temperatures from the
1971-2000 average for Lake Ontario.1
J10fall(DOY)
ScenarioaS Tmax(0C)
+1.2
A2
2011-2040
+1.1
B2
+2.2
A2
2041-2070
+2.0
B2
+4.3
A2
2071-2100
+2.9
B2
PeriodS
302.0
308.9
309.0
320.2
316.8
332.7
325.7
IPCC CO2-equivalent scenarios
a
5
IPCC CO2-equivalent scenarios
J10spring
-10.0
-12.2
-25.6
-21.3
-46.5
-30.7
J10fal
+6.9
+7.0
+18.2
+14.8
+30.7
+23.7
C L I M AT E
CHANGE
RESEARCH
I N F O R M AT I O N
NOTE
Figure 8. Difference in Tmax values from the 1971-2000 base during the 2011 to 2040, 2041 to 2070, and 2071 to 2100 periods under IPCC scenarios
A2 and B2 CO2-equivalent warming scenarios. Tmax is estimated as the median of the ten highest temperatures observed in a lake during the year.
Table 13. Predicted number of days with surface water temperatures <40C.
PeriodS
1971-2000
2011-2040
2041-2070
2071-2100
a
Lake
ScenarioaS SuperiorS
211
Base
186
A2
181
B2
159
A2
B2
169
A2
121
B2
149
Lake
Huron
163
147
144
126
132
101
118
Lake
Erie
113
95
94
77
83
52
71
Lake
Lake
ScenarioaS SuperiorS Huron
-16
-25
A2
2011-2040
-19
-30
B2
-37
A2
-52
2041-2070
-31
B2
-42
-62
-90
A2
2071-2100
-62
-45
B2
PeriodS
133
131
106
114
74
96
IPCC CO2-equivalent scenarios
a
Table 14. Predicted number of days with surface water temperatures >40C.
PeriodS
1971-2000
2011-2040
2041-2070
2071-2100
a
Table 15. Predicted differences from the 1971 to 2000 base period in the
number of days with surface water temperatures <40C.
Lake
Ontario
150
Lake
Scenario S SuperiorS
154
Base
179
A2
184
B2
206
A2
B2
196
A2
244
B2
216
a
Lake
Huron
202
218
221
239
233
264
247
Lake
Erie
252
270
271
288
282
313
294
Lake
Erie
-18
-19
-36
-30
-61
-42
Lake
Ontario
-17
-19
-44
-36
-76
-54
IPCC CO2-equivalent scenarios
Table 16. Predicted differences from the 1971 to 2000 base period in the
number of days with surface water temperatures >40C.
Lake
Ontario
215
Lake
Lake
ScenarioaS SuperiorS Huron
+16
+25
A2
2011-2040
+19
+30
B2
+37
A2
+52
2041-2070
+31
B2
+42
+62
+90
A2
2071-2100
+62
+45
B2
PeriodS
232
234
259
251
291
269
a
IPCC CO2-equivalent scenarios
Lake
Erie
+18
+19
+36
+30
+61
+42
Lake
Ontario
+17
+19
+44
+36
+76
+54
IPCC CO2-equivalent scenarios
Figure 9. Decreases in the number of days with surface water temperatures <4°C from the 1971 to 2000 base period for the 2011 to 2040, 2041 to
2070, and 2071 to 2100 periods under IPCC scenarios A2 and B2.
6
C L I M AT E
CHANGE
RESEARCH
I N F O R M AT I O N
NOTE
For Lake Huron, Lake Erie, and Lake Ontario, J10 values are predicted to change more in the spring than in the fall for
all scenarios and all time periods; for Lake Superior, the changes in the two seasons are comparable (Figure 11). This is
consistent with the empirical results of McCormick and Fahnenstiel (1999), who found that recent increases in the potential
duration of summer thermal stratification (based on the dates when water temperatures rise above 4°C in the spring and
decrease below 4°C in the fall) in several of the Great Lakes depended strongly on an earlier transition to spring conditions
rather than a later onset of fall conditions.
In general, by the 2071 to 2100 period, the J10 values for Lake Superior will have changed the most, and those for Lake
Erie will have changed the least. This reflects the findings of Dobiesz and Lester (in prep), who found that, over their 34-year
study period, the greatest increases in water temperature occurred in the colder basins (e.g., in the deep basins of Lake
Huron).
The estimated potential increases in surface water temperatures in this study could have important effects on the
fisheries and ecosystems of the Great Lakes. For example, the presence of suitable thermal habitats may increase the
number of warm-water species capable of invading the Great Lakes and may create problems for reproduction and survival
of cold-water species. Moreover, increases in water temperatures may expand the habitat for warm-water species currently
residing in the Great Lakes and shrink this habitat for cold-water species. Increases in the length of the growing season for
aquatic vegetation due to the presence of warmer temperatures for longer periods will thus have considerable effects on the
productivity of the fisheries and on the aquatic ecosystems in the lakes.
Figure 10. Differences in the number of days with surface water temperatures >4°C from the 1971 to 2000 base period for the 2011 to 2040, 2041 to
2070, and 2071 to 2100 periods under IPCC scenarios A2 and B2.
Figure 11. Estimated average annual temperature cycles for Lake Superior, Lake Huron, Lake Erie, and Lake Ontario during the 1971 to 2000
period (grey lines) and during the 2071 to 2100 period under the IPCC A2 CO2-equivalent scenario (black lines). Changes under scenario B2
were similar, and are thus not shown.
7
C L I M AT E
CHANGE
RESEARCH
I N F O R M AT I O N
NOTE
The approach we used in this study focused on predicting whole-lake average SWT. However, significant within-lake
variation in water temperatures exists between, for example, shallow embayments and open water. Future work should
focus on modelling temperature trends in the shallow basins of the Great Lakes, such as western Lake Erie and the Bay of
Quinte in Lake Ontario. In addition, we are compiling more extensive historical data sets for water temperature to develop an
independent assessment of the reliability of the SWT predictions generated by our regression models.
Acknowledgements
Funding for this project was provided by OMNR’s Climate Change Program under the auspices of Climate Change Project
CC-07/08-013. We thank Lisa Buse (OFRI, OMNR) for her editorial advice and Trudy Vaittinen (OFRI, OMNR) for formatting
this publication
References
Assel, R.A. 2005. Classification of annual Great Lakes ice cycles: Winters of 1973-2002. J. Climate 18: 4895-4904.
Austin, J.A. and S.M. Colman. 2007. Lake Superior summer water temperatures are increasing more rapidly than regional air temperatures: A positive ice–albedo feedback.
Geophys. Res. Letters 34: L06604.
Chu, C., N.E. Mandrak, and C.K. Minns. 2005. Potential impacts of climate change on the distributions of several common and rare freshwater fishes in Canada. Diversity and
Distributions 11: 299-310.
Dobiesz, N. and N. Lester. (in prep.) Changes in water clarity and temperature across the Great Lakes and their potential effect on walleye (Sander vitreus) habitat.
Ficke, A.D., C.A. Myrick and L.J. Hansen. 2007. Potential impacts of global climate change on freshwater fisheries. Rev. Fish Biol. Fisheries 17: 581-613.
Jones, M.L., B.J. Shuter, Y. Zhao and J.D. Stockwell. 2006. Forecasting effects of climate change on Great Lakes fisheries: Models that link habitat supply to population dynamics
can help. Can. J. Fish. Aquat. Sci. 63: 457-468.
Koenig, W.D. 2002. Global patterns of environmental synchrony and the Moran effect. Ecography 25: 283-288.
Magnuson, J.J., K.E. Webster, R.A. Assel, C.J. Bowser, P.J. Dillon, J.G. Eaton, H.E. Evans, E.J. Fee, R.I. Hall, L.R. Mortsch, D.W. Schindler and F.H. Quinn. 1997. Potential effects
of climate changes on aquatic systems: Laurentian Great Lakes and Precambrian Shield region. Hydrol. Proc. 11: 825-871.
McCormick, M.J. and G.L. Fahnenstiel. 1999. Recent climatic trends in nearshore water temperatures in the St. Lawrence Great Lakes. Limnol. Oceanogr. 44: 530-540.
Nakicenovic N., J. Alcamo, G. Davis, B. de Vries, J. Fenhann, S. Gaffin, K. Gregory, A. Grübler, T.Y. Jung, T. Kram, E. Lebre La Rovere, L. Michaelis, S. Mori, T. Morita, W. Pepper,
H. Pitcher, L. Price, K. Riahi, A. Roehrl, H. Rogner, A. Sankovski, M. Schlesinger, P. Shukla, S. Smith, R. Swart, S. van Rooijen, N. Victor and Z. Dadi. 2000. Special Report on
Emissions Scenarios. Intergovernmental Panel on Climate Change. Cambridge University Press. <http://www.grida.no/climate/ipcc/emission/index.htm> Accessed May 2008.
Sharma, S., D.A. Jackson, C.K. Minns and B.J. Shuter. 2007. Will northern fish populations be in hot water because of climate change? Glob. Change Biol. 13: 2052-2064.
Changements possibles, à l’avenir, des températures de l’eau de surface des Grands Lacs
en Ontario sous l’effet du changement climatique
La température est un facteur essentiel dans la productivité biologique, car il détermine les vitesses de nombreux
processus dans les écosystèmes. Plusieurs études récentes ont démontré que les températures de l’eau dans les Grands
Lacs augmentent, possiblement sous l’effet du changement climatique. Notre étude a pour but d’établir un lien entre les
changements chroniques de la température de l’eau et ceux de la température de l’air ambiant afin de produire des outils
statistiques capables de prévoir les températures futures de l’eau à partir des prévisions des températures de l’air. Des
données télédétectées ont été utilisées pour modéliser la configuration annuelle des températures de l’eau en surface
dans les lacs Supérieur, Huron, Érié et Ontario. Durant la période sans couvert glaciel, la température en surface subit
généralement une augmentation linéaire au printemps, forme un plateau à la mi-été, puis baisse de façon linéaire en
automne. Dans un lac, les vitesses de réchauffement et de refroidissement sont similaires au cours des ans, mais le
calendrier des périodes de réchauffement et de refroidissement, et des températures de plateau, affiche des variations
considérables d’une année à l’autre. Cette variation est bien prévisible en fonction de la variation de la température de l’air
ambiant. Des prévisions fondées sur le modèle canadien CGMC2 selon deux scénarios de changement climatique ont été
utilisées pour estimer les températures futures de l’eau en surface dans les lacs Supérieur, Huron, Érié et Ontario. Des
augmentations élevées des températures sont prévues. Les conséquences sur les processus des écosystèmes et sur les
pêches sont étudiées.
Cette publication hautement specialisée Potential Changes in Future Surface Water Temperatures in the Ontario Great Lakes as a
Result of Climate Change, n’est disponible qu’en Anglais en vertu du Règlement 411/97 qui en exempte l’application de la Loi sur les ser
les services en français. Pour obtenir de l’aide en français, veuillez communiquer avec au ministère des Richesses naturelles au information.
52176
(0.3k P.R., 08 07 15)
ISBN 978-1-4249-3366-2 (PDF)
2008, Queen’s Printer for Ontario
Printed in Ontario, Canada
8
This paper contains recycled materials